Currently, all spacecraft require constant power from an electrical power source to support the operation of control actuators, to power the payload, to maintain thermal stability, and to control a host of other functions. An example of such a spacecraft, employs a reaction wheel system that is configured in a pyramid for attitude control while utilizing photovoltaic arrays for electrical power. An inherent limitation of this system and others that rely on electrical power is that these systems cannot be used during a solar eclipse without the use of an auxiliary power source.
Accordingly, all current spacecraft require some source of stored electrical power or auxiliary power to maintain their subsystem functionalities during an eclipse in addition to requiring an electric power source to support the operation of normal spacecraft functions. These stored or auxiliary power sources include, for example, batteries or other similar devices. Currently, if a spacecraft does not utilize some source of stored or auxiliary power to control its attitude, the spacecraft will lose power upon entering an eclipse, potentially causing the spacecraft attitude to deteriorate to a state causing permanent damage to vital spacecraft systems. Moreover, these spacecrafts that carry auxiliary power sources, such as batteries, carry additional weight which can decrease the payload capacity and also increase the cost of manufacturing and operation of the spacecraft. Therefore, a spacecraft that can maintain stability through an eclipse without the need for auxiliary power would be desirable.
While the use of a momentum bias to induce passive attitude stabilization in a spacecraft is well known, there are, however, no known methods or apparatus that utilize a momentum bias for eclipse storage on a spacecraft without dependence on auxiliary power. Moreover, there are no known methods or apparatus that utilize a momentum bias for eclipse storage on a spacecraft that is designed to be actively controlled in three axis during periods of sunlight.